1. Technical Field
The present invention generally relates to a gas water heater, and more particularly to a method of ensuring the safety of exhaust of a water heater.
2. Description of Related Art
Water heaters which exhaust by natural convection usually provide poor ventilation performance, and therefore may not be able to effectively exhaust carbon monoxide produced by incomplete combustion, which may cause serious injury or even death.
In general, a water heater provided with a blower could avoid the above situation, wherein the blower could supply air for combustion and enhance the ventilation conditions inside the water heater. Furthermore, the water heater could also achieve better heating efficiency.
However, if the blower becomes aged, or the exhaust pipe used for exhausting carbon monoxide is seriously blocked, the ventilation condition within the water heater would be harmed, leading to a higher risk of accumulating carbon monoxide. What's worse, the user may feel confident about this type of water heater, and therefore may put himself in danger without realizing it.
The conventional method of ensuring safety for water heaters usually determines the status of the exhaust pipe and the aging condition of the blower by detecting the rotational speed of the motor of the blower. Typically, a comparison criterion based on a reasonable rotational speed range is predetermined, which is adapted to check the rotational speed of the motor. If the rotational speed of the motor is higher than the highest threshold value of the rotational speed range, the exhaust pipe is considered to be blocked; if the rotational speed of the motor is lower than the lowest threshold, the blower is considered having the problem of aging.
Though the conventional method of ensuring safety for water heaters could increase the safety of using a water heater, there are still some restrictions. In practice, if the exhaust pipe connected to the water heater is longer than usual, or has several turns, the air pressure for exhausting would be higher in the first place, which causes the initial rotational speed of the motor higher. In such a condition, the rotational speed of the motor would exceed the highest threshold easily simply because there is wind blowing into the exhaust pipe from outside, or because the exhaust pipe is slightly covered. In other words, the blocking condition of the exhaust pipe may be incorrectly determined.